There are 4 personal titles that are used a lot in the English language. Mr. Mrs. Miss and Ms. In the UK, you do not use periods after the abbreviations of personal titles, but in the USA and Canada you do use periods.
You use titles with people who are older than you or who you respect. Depending on your work environment you may or may not call your boss by their personal title and last name. At my job we call everyone by their first names, even the CEO of the company. However, if you work at a school, even the teachers call each other using their personal titles because they want the students to do the same.
Here in the South, they also have a new use of personal titles. My children’s friends call me, “Ms. Yvonne.” In many other states (like Texas) they would call me, “Mrs. Crawford.” So, some of this is regional.
Mr. is used for married and unmarried males. Mr. is followed by the last name of the person. In mailings you can either put both the first and last name or just the last name depending on how formal you would like to be. For young boys you can use “Master,” but this is not the norm in the USA.
Mr. Brian Crawford (on a formal letter)
Mr. Crawford (in conversation)
Miss is used for young unmarried women.
Miss Amelia Crabtree (on a formal letter)
Miss Crabtree (in conversation)
Mrs. is used for married women or women who are old enough to be married.
Mrs. Yvonne Crawford (on a formal letter)
Mrs. Crawford (in conversation)
Ms. is a newer title for women. It’s used for when you aren’t quite sure whether or not the person is married or not, so you can just say Ms.
Ms. Alexandra Culpepper
Ms. Yvonne (Like stated above, in the South, kids will call their friend’s parents by their first name but add Ms. in front of it.)